I recently replaced the leaking pinion oil seal on my 1985 Toyota Pickup 4wd. I made a video showing how I replaced the seal without replacing the pinion crush sleeve and having to reset all the preloads, requiring complete disassembly of the 3rd member:

If you want to see the entire process to replace the crush sleeve, check preload and re-torque everything, here are scans from the 1985 Toyota Factory Service Manual.  Click for high resolution: